Raw material shortages: substitution offset

The EU has been trying to develop plans that will ensure industry access to raw materials such as rare metals and earths. One route that is quietly developing is that of substitution.

European Union ministers have been developing plans to ensure industries get better access to raw materials, as competition for access to commodities such as rare metals becomes fiercer with globalisation. The strategy, overlooking substitution, has suggested:

Raw materials considered as "potentially critical" for 'high tech' sectors and the economies of developed countries, include niobium, platinum, manganese and titanium. Platinum and palladium, for instance, are used in the fuel cells that power hydrogen cars, sillicon, gallium and silver are used in solar cells. Cu-Indium-Gallium-Selenium (CIGS) alloys are needed in "thin-film" photovoltaic solar cells. Indium is used to manufacture microprocessors an udltra-small RFID chips

A French study identified short to medium-term risks to their supply of a number of materials: antimony, chromite, cobalt, germanium, gallium, indium, lithium, magnesium, molybdenum, platinum, palladium, rhodium, rare earths, rhenium, titanium and tungsten.

EMPA MEETING
The Swiss Federal labs for Materials and technology Empa researchers and representatives from industry explained at a recent Technology Briefing not only why scarce metals are essential for many key technologies but how an impending scarcity might be avoided.

"There is no future without scarce metals!" was the how Peter Hofer, a member of Empa's board of directors, greeted guests at the recent Technology Briefing on scarce metals held at the Empa Academy, reports Renewable Energy Focus "Materials with special properties are essential if we are to find solutions to the problems caused by our ever-increasing mobility requirements."

Scarce metals include the rare earth metals which are used (together with iron and boron), for example, to make the very strong magnets needed in wind turbines.

Manufacturers like to use tantalum for the capacitors on mobile telephone printed circuit boards (PCBs) because this transition metal, when used in these tiny components, enables them to store and release large amounts of electrical energy. The demand is high, more than 60% of the tantalum mined being used for this application.

But explained scarce metals expert, Patrick Wäger, raw materials which can only be mined and refined in a few countries, for which alternatives are not easy to find and which have a low rate of recycling, must are considered to be critical.

China, for example, almost completely controls the supply of rare earth metals from which high-performance permanent magnets are manufactured. Wäger, a staff member of Empa’s Technology and Society laboratory, added that by imposing export restrictions the Chinese government has forced prices to rise, leading to delivery bottlenecks.

Great efforts are being made to reduce this dependency, expanding supply capacities outside of China, in the USA, Australia or Greenland – with environmental implications.

Tantalum, required for high-performance micro-capacitors, is viewed in the microelectronics industry as a material which is difficult to substitute, and to date it has not been possible to recover it from end-of-life products. Tantalum is illegally mined in certain Central African countries under degrading conditions, and its sale profits used to finance civil wars.

"Swiss companies also need to think closely about how they can reduce this dependency and avoid the possibility of delivery bottlenecks," says Jean-Philippe Kohl, (right) head of Swissmem's Economic Policy Group. A recent survey of members in the Swiss mechanical engineering, electrical and metal sectors showed that every company used at least one of the critical raw materials.

To protect themselves from possible shortages many signed long-term delivery contracts with their suppliers. Others however are cooperating with research institutions to ptimise existing processes or develop alternative raw materials and technologies.
Research lab alternatives

SUBSTITUTION APPROACHESBack in August last year, Michael Lebby GM of Palo Alto based Translucent noted, “We are bringing a decade of Translucent REO epitaxial experience to bear on the challenge of enabling GaN growth to scale cost-effectively well beyond current limitations.

Our vGaN platform is an ‘on-silicon’ technology, allowing us to harness mature silicon-substrate technologies and their low costs, and we expect this to have an extremely beneficial impact in driving down costs for GaN-based LEDs and FETs

Adopting this style of approach, Stephan Buecheler explains how Empa's Thin-Films and Photovoltaic laboratory is working to reduce tellurium layer thickness in flexible solar cells which use cadmium telluride (CdTe) as the active material.

Similarly, efforts are being made in PV based on copper-indium-gallium-diselenide (CIGS) to replace the indium oxide with zinc oxide.

In making these changes no loss of performance is expected, rather an increase in the efficiency of devices by optimal use of raw materials and fast processes. Researchers already shown this is possible, having set a new efficiency record last year.

The institution’s Internal Combustion Engine laboratory has developed an extremely efficient and economic foam catalyst. Changing the form of the ceramic substrate, has enabled the use of less of the noble metals palladium and rhodium in comparison to conventional catalysts.

In collaboration with Empa's Solid-State Chemistry and Catalysis laboratory, the motor scientists are conducting research work on regenerative exhaust gas catalysts which instead of scarce metals use perovskites . These are multifunctional metal oxides with specialised crystal structure, capable of transforming heat directly to electrical energy.